Figure 6.

Epitope-tagged PIPKIIα and PIPKIIβ localized to nuclei and nuclear speckles when expressed in cultured fibroblasts. Indirect immunofluorescence was performed on formaldehyde-fixed human 2RA fibroblasts transiently overexpressing FLAG epitope-tagged PIPKIIα or PIPKIIβ. Double labeling with anti-PIPKIIα or PIPKIIβ antibodies and anti-FLAG M2 antibodies showed primarily diffuse nuclear localization of the expressed kinases (top row). Localization of overexpressed kinases to the speckles was revealed by a very brief preextraction of the cells with 0.2% Triton X-100 (bottom row) and staining with anti-FLAG antibody. Speckles were costained with the human Sm serum. Bar, 10 μm.